This invention relates to a dialysis device, and more particularly, to an improved casing; for partially enclosing a stack formed of a plurality of parallel membrane support plates and membranes.
In U.S. Pat. application Ser. No. 732,232 filed on the same day as this application in the names of Jimmy L. Miller and William J. Schnell, entitled "Distribution System For Blood Treatment Apparatus" and assigned to the assignee of the present invention, there is disclosed an apparatus for dialyzing or oxygenating blood utilizing the transfer of fluid through a membrane. As disclosed in that patent application, a plurality of membrane support plates are provided with each membrane support plate supporting a membrane on opposite sides thereof. A blood path is formed between adjacent membranes and a dialysate path is formed between adjacent membranes and its respective membrane support plate. In the illustrative embodiment, the membranes and membrane support plates form a generally rectilinear stack. Although no limitation is intended, the present invention is well suited for use as a casing to enclose the rectilinear stack of membranes and membrane support plates disclosed in the above-identified patent application.
The U.S. patent to Riede, et al. U.S. Pat. No. 3,734,298 discloses a casing for use with a stack of membranes and membrane support plates. The casing disclosed therein is formed of a pair of clamping plates and clamping rails which dovetail into grooves provided along the sides of the clamping plates. However, while the size of the stack of membranes and membrane support plates may vary somewhat, the casing size is fixed and invariable. Thus the pressure of the casing upon the membranes and membrane support plates may be too great or too small depending upon the thickness of the stack of membranes and membrane support plates enclosed by the casing. As a result, the distances between the membrane support surfaces of the membrane support plates may vary from one dialysis device to another because of the possible variation in the forces exerted by the casing against the stack.
In contrast, the present invention provides a casing which permits the proper pressure to be exerted on the sealing surfaces of the membranes and plates. This results in a predetermined sealing force and the membrane support surfaces of the membrane support plates will be spaced a predetermined distance from each other, thereby permitting a constant priming volume in the blood compartment of the dialyzer.
It is, therefore, an object of the invention to provide a casing having variable dimensions during construction thereof, whereby appropriate pressure on the stack of membranes and membrane support plates can be applied.
Another object of the present invention is to provide a casing which permits a constant priming volume in the blood compartment of a dialyzer.
A further object of the present invention is to provide a casing which is simple in construction and efficient to manufacture.
To this end, among other things the casing has hollowed-out portions defined by ribs which aid in maintaining the rigidity of the unit. A separate plate overlies the ribs and is scan-welded to the device to form a very rigid unit that is effectively sealed and is economical and efficient to produce.
Other objects and advantages of the pesent invention will become apparent as the description proceeds.